Device for dispensing a volatile liquid using a wick in an ambient air stream

ABSTRACT

A wick-based emanation device for dispensing a volatile liquid is disclosed. The dispensing device includes a housing and a fan mounted in the housing for generating an air stream used for dispersing the volatile liquid. Walls of the housing form an enclosure for mounting the fan and for receiving an exposed portion of the wick therein. A retention structure is provided for coupling the wick to the housing and securing the wick in the air stream generated by the fan. The volatile liquid migrates along the wick from the reservoir to the exterior of the container where it is evaporated from the surface of the wick by forced airflow generated by a motorized fan mounted in the housing. The wick is formed to have a width dimension W which does not exceed 1.2 times a dimension R of a blade of the fan extending from the fan axis of rotation to an edge of the fan blade farthest from the axis of rotation.

FIELD OF THE INVENTION

[0001] The present invention relates to emanation systems for volatileliquids and, more particularly, to a wick-based emanation systemincorporating a fan mounted in a housing for dispersing the volatileliquid.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002]FIG. 1 is a perspective view showing insertion of a wick into ahousing of a dispensing device of the present invention;

[0003]FIG. 2 is a front view of the dispenser of FIG. 1 showing thedispenser housing partially cut away with the wick positioned in thehousing;

[0004]FIG. 3 is a side view showing the dispenser housing partially cutaway with the wick positioned in the housing as shown in FIG. 2;

[0005]FIG. 4 is a front view of a fan blade assembly mounted in thedispenser housing as shown in FIG. 2;

[0006]FIG. 5 is a front view of the wick secured in a container forinsertion into the housing of the dispensing device as shown in FIG. 1;

[0007]FIG. 5A is a cross sectional view of the wick of FIG. 5 takenalong line 5A-5A transverse to a length of the wick;

[0008]FIG. 6 is a cross-sectional view of the wick of FIG. 3 taken alonga length of the wick;

[0009]FIG. 7 is a side view of an embodiment of the wick;

[0010]FIG. 7A is a top view of the wick of FIG. 7;

[0011]FIG. 7B is a cross-sectional view of the wick of FIG. 7A takenalong line B-B in FIG. 7A;

[0012]FIG. 8A is a top view of another embodiment of the wick;

[0013]FIG. 8B is a cross-sectional view of the wick of FIG. 8A takenalong line A-A in FIG. 8A;

[0014]FIG. 9A is a top view of still another embodiment of the wick;

[0015]FIG. 9B is a side view of the wick in FIG. 9A; and

[0016]FIG. 10 is an exploded view of a wick secured in a container asseen in FIG. 1.

DETAILED DECSRIPTION OF THE INVENTION

[0017] Referring to FIGS. 1-3, volatile liquid dispenser 10 is designedto disseminate a volatile liquid, such as a fragrance compound, into aroom. The fragrance compound is disseminated via a forced air streamflowing around a wick 310 at room ambient temperature. According to thepresent invention, dispenser 10 includes a housing 30, a motorized fan32 mounted in housing 30 for generating an air stream, and a wick 310coupled to housing 30. Housing 30 includes a front wall 34, a side 36formed at each lateral end of front wall 34, and a rear wall 38 formedopposite front wall 34. Front wall 34, sides 36, and rear wall 38combine to form an enclosure 40 for housing fan 32 and for receivingwick 310 into the air stream generated by fan 32. One or more air inletports (not shown) may be formed in rear wall 38 for providing intake airfor fan 32. Also, one or more air outflow ports 42 are provided in frontwall 34 to provide a path for outflow of the air stream from enclosure40. A lower portion of housing 30 forms a base 44 configured to enabledispenser 10 to rest on a flat surface. A switch or button (not shown)may be provided on an exterior surface of housing 30 to enableactivation and deactivation of the fan motor.

[0018] Referring to FIGS. 3, 4 and 6, fan 32 is powered by a battery(not shown) positioned in base 44 of housing 30. Access to the batterymay be provided by a hinged or removable access plate formed in base 44.Fan 32 includes a plurality of fan blades 48 that rotate about a fanaxis of rotation 50 during operation of the fan. During rotation, fanblades 48 trace out a circumferential path 52. As shown in FIG. 4, fanblades 48 each have a dimension R extending from axis of rotation 50 toan edge 54 of the respective fan blade 48 farthest from axis of rotation50.

[0019] Referring to FIG. 2, in the present invention the size of aprofile of wick 310 immersed in the air stream is controlled relative tothe size of fan 32 used to generate the air stream. To accomplish this,wick 310 is formed to have a width dimension W, as shown in FIG. 6,which does not exceed 1.2 times the dimension R (FIG. 4) extending fromaxis of rotation 50 to the edge 54 of any fan blade 48 farthest fromaxis of rotation 50. In the embodiment shown, R=21.15 mm and W=12.7 mm.Width dimension W may be measured transverse to rotational axis 50 ofthe fan. Width dimension W may also be measured transverse to a lengthdimension of wick 310.

[0020] In alternative embodiments, wick 310 may be formed to have awidth dimension W which does not exceed 80 times the dimension R, 0.60times the dimension R, etc.

[0021] Referring now to FIGS. 1 and 7-10, wick 310 is to be positionedand secured in enclosure 40 formed by housing 30 and so as to reside inthe air stream generated by fan 32. Wick 310 may be secured in thedesired position by coupling wick 310 to dispenser housing 30 using anyone of numerous methods.

[0022] Referring to FIGS. 1-3, in one embodiment wick 310 may be securedin a container 20 holding the volatile liquid to be dispensed. A portionof wick 310 is in communication with the volatile liquid in container20. Another portion of wick 310 extends outside container 20 forimmersion into the air stream.

[0023] Referring to FIGS. 3 and 5, in one embodiment, wick 310 issecured in a container 20 holding the volatile liquid. A portion of wick310 extends into an interior of container 20 to contact the volatileliquid. Referring to FIG. 3, dispenser housing 30 has opposing sidewalls41 and 71. Each of opposing sidewalls 41 and 71 has a corresponding edgeportion 52 and 54, respectively. Edge portions 52, 54 define an openingadapted to receive wick 310 and a portion of container 20 into enclosure40. A retention structure is formed along one or more of opposing sidesof container 20 to help position and releasably secure container 20between opposing sidewalls 41 and 71 of housing 30. The retentionstructure may be formed integral with container 20. When container 20 issecured to dispenser housing 30 as described above, wick 310 ispositioned in the air stream generated by fan 32. As seen in FIGS. 2 and3, when wick 310 is in its desired position within enclosure 40, wick isspaced apart from any interior surface of housing 30. Also, as seen inFIGS. 2 and 3, wick 310 may be positioned along the fan rotational axis50.

[0024] In an alternative embodiment (not shown), a receptacle for wick310 may be formed on dispenser housing 30 for placement of wick 310directly therein. The receptacle would be positioned on dispenserhousing 30 such that a wick received therein resides in an air streamgenerated by fan 32 as described above.

[0025] Examples of other retention structures suitable for the purposedescribed above are disclosed in co-pending patent application entitled“Container For A Device For Dispensing Volatile Liquid”, incorporatedherein by reference, and filed Mar. 21, 2003.

[0026] As stated previously, the volatile liquid migrates along wick 310from the reservoir to the exterior of container 20 where it isevaporated from the surface of wick 310 by forced airflow generated by amotorized fan mounted in housing 100. Detailed descriptions of somerepresentative wick structures which may be incorporated into thedispenser of the present invention are provided in co-pending patentapplications having U.S. Ser. Nos. 10/266,512; 10/266,798; and10/266,546 and are incorporated herein by reference.

[0027] Referring to FIG. 10, a portion of wick 310 that is co-extensivewith neck 330 of container 20 is shaped so that it fits snugly into theneck 330 of the container 20. The wick 310 is long enough so that itsbottom surfaces come into contact with the liquid in the container 20and its top surfaces are exposed to the ambient air. (The level of theliquid is not shown in the container 20.) It is preferable to use a neckclosure 320, such as that shown in FIG. 10, to hold the wick 310 inplace and to prevent leakage around the neck 330 of the container 20.The fit between the neck closure 320 and the container 20 is tightenough to prevent leakage of the liquid from the container 20. Likewise,the fit between the neck closure 320 and the wick 310 is sufficientlytight to prevent leakage of the liquid from the container 20.

[0028] In addition, the neck 330 of the container 20 may be shaped sothat a cover 300 can be securely fastened over the wick 310 and neckclosure 320. For example, the outer neck 330 of the container 20 may bethreaded so that cover 330 can be screwed on top of the container 20when the device is not in use.

[0029] Referring again to FIG. 10, the container 20 and the neck closure320 can be made of any suitable material that is leakproof and adaptableto incorporate the characteristics of the retention structureembodiments described herein. The size of the opening in the container20 and the size of the neck closure 320 are dependent upon each otherand upon the size of the wick 310 that is to be used with the device.

[0030] The neck closure 320 or neck 330 of the container 20 may beformed with a small hole (e.g., a vent-hole) to help counter the effectsof a vacuum that can form in the head-space of the container 20. Thewick 310 transports the liquid to the surface of the wick 310 by aprinciple called capillary action. In particular, the wick materialcontains numerous pores, and these pores act as capillaries, which causethe liquid to be drawn into them. As the liquid is drawn from thecontainer and transported up the porous wick 310, a vacuum is created inthe head-space of the container 20. The formation of a vacuum in thehead-space of the container 20 decreases the rate that the liquid iswicked from the reservoir to the surface. This decrease in the wickingrate translates directly into a decrease in the release rate of theliquid to the ambient air. Accordingly, in order to combat the formationof the vacuum in the head-space, it is often preferable to form avent-hole in the vicinity of the head-space of the container 20.However, if the container 20 is overturned, either during shipping or,later, during handling of the bottle by the consumer, it is possible forthe concentrated liquid in the container 20 to leak out of thevent-hole. Therefore, if is preferable to design a device that does notrequire a vent-hole.

[0031] It has been found that if the pore size of the wick 310 is belowa critical size, the vent-hole can be eliminated without sacrificing therelease rate of the vaporizable liquid into the ambient air. Because thecapillary force increases as the pore size of the wick 310 decreases, awick 310 with very small porosity has a very strong capillary force.This strong capillary force allows the wick 310 to continue to be ableto transport the liquid from the container 20 to the surface of the wick310 even though a vacuum has formed in the head-space of the container20. In other words, a wick 310 with a very small pore size is able toovercome the vacuum effect that is present in the head-space of thecontainer 20.

[0032] The critical size of the wick 310 is determined by the surfacetension of the liquid, the compatibility of the wick 310 and liquid(i.e., the contact angle), and the extent to which a vacuum is generatedwith the head-space of the container 20. In particular, we have foundthat if the wick 310 is manufactured with a mean pore size that is belowabout four microns, the effects of a vacuum in the head-space of thecontainer 20 can be greatly decreased. Specifically, we have found thatit is most preferable that the mean pore size of the wick 310 be belowabout one micron. When the wick 310 has a mean pore size of below fourmicrons, and preferably below one micron, we have found that the wick310 is still able to effectively function to transport the liquid fromthe container 20 to the surface of the wick 310.

[0033] When using a device of this invention, it is not necessary toprovide a vent-hole in the upper part of the container 20, or in theneck closure 320 because the vacuum effects are substantially decreased.By eliminating the vent-hole, the problem of spillage or leakage thatoccurs as a result of the existence of the vent-hole is also eliminated.

[0034] The mean pore size of the wick 310 can be determined by anystandard test for determining porosity and pore size distribution. Forexample, mercury porosimetry is a method that gives information onporosity and pore size distribution for rigid wicks. It is based on themeasurement of differential increments in the amount of mercury intrudedinto the wick 310 as a function of increasing applied pressure.

[0035] It has also been found that another advantage in using a wick 310with a mean porosity of below about four microns, and preferably belowabout one micron, is that the lower porosity decreases the likelihood ofthe liquid spilling or leaking through the wick 310 itself. Since theupper surface of the wick 310 is exposed to the ambient air, if thecontainer 20 is overturned, it is possible for liquid to leak outthrough a wick of conventional pore sizes. Using a smaller porosity wick310 of this invention, however, decreases the ability of the liquid totravel through the wick 310 when the container 20 is overturned.

[0036] The wick 310 can be made of a variety of materials. It ispreferable that the wick 310 be rigid enough to provide minimal contactarea with the surface that the wick 310 comes in contact with. Polymericwicks, for example, have been found to be effective for these purposes.In particular, wicks composed of ultra high molecular weight, highdensity polyethylene (HDPE) have been found to be suitable. Such wicksare generally comprised of blends of HDPE in particle form, and theblends are developed to meet the target pore characteristics of the wick310.

[0037] Preferably, the solubility parameter of the polymer used in thewick 310 is significantly different from that of any of the componentscontained in the liquid. This prevents the wick 310 from swelling (orother changes) that may lead to a change in the pore size and porosityof the wick 310, which would consequently affect the release rate of thevaporizable liquid into the ambient air.

[0038] The wick 310 can also be made in a variety of shapes. FIG. 10,for example, shows a cylindrical wick 310 with a narrower lower region.This change in shape of the wick 310 is not required. Instead, thisvariation in shape can be useful in that it both increases the amount ofthe surface area of the wick 310 that is exposed to the ambient air andaids in forming a tighter seal at the neck 330 area of the container 20,thus helping to prevent spilling or leaking of the liquid from thecontainer 20. The above-described benefits of using a wick 310 with amean pore size of below about four microns, and preferably below aboutone micron, can be obtained with wicks of many different shapes.

[0039] Referring to FIGS.5 and 5A, it may be seen that wick 310 iselongate and has a longitudinal axis 60. It may also be seen that across section (FIG. 5A) of the wick transverse to longitudinal axis 60has a perimeter that is generally circular in shape. In alternativeembodiments (not shown), wick 310 may be constructed such that theperimeter of the cross section of wick 310 transverse to longitudinalaxis 60 has any one of several geometric shapes. For example, the shapeof the perimeter of the wick cross section may be hexagonal,rectangular, triangular, elliptical, etc. The ability to form a wickhaving any of a variety of cross-sectional shapes provides an additionalmethod for controlling the surface area of the wick to be immersed inthe airflow.

[0040] As shown in FIG. 7, it is also possible to provide a wick 310with an outer layer that is made up of a material with larger poresizes. In FIG. 7, the large pore outer section 310 b completelysurrounds the exposed portion of the wick 310 a. The small pore sizesection 310 a extends into the container 20 and is in contact with theliquid. In this manner, the smaller pores of the inner portion 310 a ofthe wick 310 allow the delivery system to be constructed without avent-hole, while the larger pores of the outer portion 310 b provide amaximum release rate of the vaporizable liquid off the surface of thewick 310 that is exposed to the ambient air. It should be noted,however, that the large pore section 310 b need not completely surroundthe upper region of the small pore section 310 a as shown in FIG. 7 inorder to provide the benefits of this invention.

[0041] It is often desired that the volatile liquid dispenser describedherein exhibit an initial spike in the release rate of the volatileliquid when the device is first activated. For example, when a fragrancedispensing device is activated, an initial spike in the release rate ofthe volatile liquid fragrance compound is desired in order to quicklydisperse into the air a sufficient amount of the fragrance compound toeffectively decrease the number of insects in the surrounding area. Oncean optimum level of fragrance compound is present in the ambient air ofthe operating area, however, the release rate of the fragrance compoundshould be decreased to an amount that is sufficient to maintain thatoptimum level. By having two sections of varying pore size exposed tothe ambient air at the same time, it is possible to achieve an initialspike effect.

[0042] Referring to FIGS. 7A, 7B, 8A, 8B, 9A and 9B, in variousembodiments of the wick, the initial spike effect described above may beachieved by having a wick 310 that is comprised of at least twosections. A first section 350 is made of a material that has apredetermined pore size, while the second section 360 is made of amaterial that has a pore size that is greater than that of the materialof the first section. Both sections of the wick are exposed to theambient air.

[0043] In the wick embodiments described above, the cylindrical shape ofthe large pore section 360 is also narrowed at its lower portion. Thepore size of the lower portion of large pore section 360, however, doesnot change with this change in diameter. Importantly, this change inshape is not required for achieving the initial spike effect. Instead,this variation in shape can be useful in that it both increases theamount of the surface area exposed to the ambient air and aids informing a tighter seal at the neck 330 area of the container 20 (FIG.10), thus helping to prevent spilling or leaking of the liquid from thecontainer 20.

[0044] In the above-described embodiments, the wick is longitudinal, hasa longitudinal axis and a curved exterior surface. In alternativeembodiments, the wick may be formed such that a cross-section of thewick taken perpendicular to the longitudinal axis has any one of avariety of simple geometric shapes, such as a circle, a diamond, arectangle, a hexagon, an octagon, an oval or a triangle.

[0045] Industrial Applicability

[0046] The present invention provides a structure and method forcontrolling the size of a profile of a wick immersed in an air streamrelative to the size of a fan used to generate the air stream. Thisallows the resistance to the air stream produced by the wick to beminimized. When combined with the positioning of the wick within the airstream, this enables the linear velocity of the air flowing around thewick to be maximized, thereby ensuring rapid and efficient disseminationof a volatile substance drawn through the wick from a reservoir.

[0047] It should be understood that the preceding is merely a detaileddescription of various embodiments of this invention and that numerouschanges to the disclosed embodiment can be made in accordance with thedisclosure herein without departing from the spirit or scope of theinvention. The preceding description, therefore, is not meant to limitthe scope of the invention. Rather, the scope of the invention is to bedetermined only by the appended claims and their equivalents.

1. A dispenser for a volatile liquid, comprising: a fan mounted to ahousing for generating an air stream, a blade of the fan having adimension R extending from an axis of rotation of the fan blade to anedge of the fan blade farthest from the axis of rotation; and a portionof a wick positioned to be immersed in an air stream generated by thefan, the wick having a width W which does not exceed 1.2R.
 2. Thedispenser of claim 1 wherein the wick has a longitudinal axis and across section of the wick transverse to the longitudinal axis has aperimeter that defines a simple geometric shape.
 3. The dispenser ofclaim 2 wherein the perimeter of the wick cross section is rectangular.4. The dispenser of claim 2 wherein the perimeter of the wick crosssection is square.
 5. The dispenser of claim 1 wherein a portion of thewick is in communication with the volatile liquid.
 6. The dispenser ofclaim 2 wherein the perimeter of the wick cross section is hexagonal. 7.The dispenser of claim 2 wherein the perimeter of the wick cross sectionis circular.
 8. The dispenser of claim 2 wherein the perimeter of thewick cross section is elliptical.
 9. The dispenser of claim 2 whereinthe perimeter of the wick cross section is triangular.
 10. The dispenserof claim 1 in which the wick includes a first and second section. 11.The dispenser of claim 10 in which the portion of the wick positioned tobe immersed in the air stream includes both a first and second sections.12. The dispenser of claim 10-in which the first section is formedhaving a predetermined pore size and the second section is formed havinga predetermined pore size that is greater than the pore size of thefirst section.
 13. The dispenser of claim 12 wherein the ratio of thepore size of the second section to that of the first section is greaterthan approximately two.
 14. The dispenser of claim 10 wherein the firstsection is formed on top of the second section.
 15. The dispenser ofclaim 10 wherein each of the first section and the second section iscylindrical in shape.
 16. The dispenser of claim 1 wherein the wick hasa curved exterior surface.
 17. The dispenser of claim 1 wherein the wickis elongate.
 18. The dispenser of claim 17 wherein the wick has alongitudinal axis and the width W is measured transverse to thelongitudinal axis of the wick.
 19. The dispenser of claim 1 wherein thewick has a predetermined mean pore size of less than about four microns.20. The dispenser of claim 19 wherein the wick is comprised of highdensity polyethylene.
 21. The dispenser of claim 19 further comprisingan outer layer of porous material that surrounds at least a portion ofthe surface of the wick that is positioned to be immersed in the airstream, wherein the outer layer has a predetermined mean pore size thatis greater than that of the wick.
 22. The dispenser of claim 21 whereinthe outer layer completely surrounds the surface of the wick that ispositioned to be immersed in the air stream.
 23. The dispenser of claim1 wherein the wick has a predetermined mean pore size of less than aboutone micron.
 24. The dispenser of claim 23 wherein the wick is comprisedof high density polyethylene.
 25. The dispenser of claim 23 comprisingan outer layer of porous material that surrounds at least a portion ofthe surface of the wick that is positioned to be immersed in the airstream, wherein the outer layer has a predetermined mean pore size thatis greater than that of the wick.
 26. The dispenser of claim 25 whereinthe outer layer completely surrounds that surface of the wick that ispositioned to be immersed in the air stream.
 27. The dispenser of claim1 wherein the wick is positioned along an axis of rotation of the fan.28. The dispenser of claim 1 wherein the wick is spaced apart from anyinterior surface of the housing.
 29. The dispenser of claim 1 whereinthe wick has a length and the width W is measured transverse to thelength of the wick.
 30. The dispenser of claim 1 wherein the width W ismeasured transverse to an axis of rotation of the fan.
 31. The dispenserof claim 1 wherein width W which does not exceed R.
 32. The dispenser ofclaim 1 wherein width W which does not exceed 0.8R.
 33. The dispenser ofclaim 1 wherein width W which does not exceed 0.6R.
 34. The dispenser ofclaim 1 wherein width W which does not exceed 0.4R.
 35. The dispenser ofclaim 1 wherein width W which does not exceed 0.2R.
 36. A method forassembling a dispenser for a volatile liquid, comprising the steps of:providing a fan mounted to a housing for generating an air stream inwhich a blade of the fan has a dimension R extending from an axis ofrotation of the fan blade to an edge of the fan blade farthest from theaxis of rotation; and positioning a wick to be immersed in an air streamgenerated by the fan in which the wick has a width W which does notexceed 1.2 R.
 37. The method of claim 36 in which the step ofpositioning includes providing a wick with the width W which does notexceed R.
 38. The method of claim 36 in which the step of positioningincludes providing a wick with the width W which does not exceed 0.8 R.39. The method of claim 36 in which the step of positioning includesproviding a wick with the width W which does not exceed 0.6 R.
 40. Themethod of claim 36 in which the step of positioning includes providing awick with the width W which does not exceed 0.4 R.
 41. The method ofclaim 36 in which the step of positioning includes providing a wick withthe width W which does not exceed 0.2 R.
 42. The method of claim 34 inwhich the step of positioning includes providing a wick having aperimeter of a cross section of the wick taken transverse to a length ofthe wick to include one of a rectangle, square, hexagon, octagon,circle, ellipse and a triangle.
 43. The method of claim 34 in which thestep of positioning includes positioning the wick along the axis ofrotation of the fan.
 44. The method of claim 34 in which the step ofpositioning includes positioning the wick spaced apart from an interiorsurface of the housing.